Direct relationship between the system cooling load and indoor heat gain in a non-uniform indoor environment

Abstract

An accurate assessment of the system cooling load (SCL) is crucial in sizing air-conditioning systems for buildings. However, there is no explicit relationship between the SCL and heat gain in non-uniform indoor environments oriented to local requirements. To address this issue, a direct relationship between them was derived theoretically based on the average accessibility of heat sources, which quantifies the influence of each heat source on the local zone. Twenty-two cases in an office with different air distributions, target zones, and heat source scenarios were designed to further demonstrate it. The results indicate that (1) the established relationship reveals the influence rules of the heat gain on the SCL; (2) the established relationship allows the fast prediction of the SCL, which only conducted 1 and 4 simulations for obtaining the SCLs in 5 cases with different target zones and 16 cases with different heat source scenarios, respectively; (3) the advanced air distributions only provide the potential of decreasing the SCL, its implementation is mainly decided by the fresh-air ratio, and achieved the decrease rates of 0–38.1% in the cases with different fresh-air ratios. This study will be beneficial for designing and operating air-conditioning systems in non-uniform indoor environments.